Hot topics in musculoskeletal ultrasound

Abstract

The topics chosen for discussion in this presentation include commonly encountered conditions and scenarios that seem to cause difficulties and confusion for sonographers and radiologists. A good place to start is the vexed issue of subacromial bursitis and impingement. ‘Subacromial bursitis’ is often reported on ultrasound due to apparent thickening of the bursa. This thickening may be accentuated in abduction (‘bursal bunching’) and accompanied by pain leading to the reporting of ‘impingement’. The lack of clear evidence as to what constitutes a thickened bursa, and the meaning of the term ‘impingement’ will be explored. Another common scenario is ultrasound of the adult hip for ‘trochanteric bursitis’. Multiple bursa compartments are present between and adjacent to the tendons and muscles near the greater trochanter, and thin slips of fluid in these spaces are common. Pathologically proven trochanteric bursitis is uncommon, and usually associated with pathology of the gluteal tendons. Pain at the greater trochanter is very common, especially in elderly people. ‘Trochanteric bursitis’ is best thought of as a regional pain syndrome with various causes. The dominant role for ultrasound in this context is guidance of injection of steroid and local anaesthetic. Ultrasound of soft tissue masses is common, and usually straightforward in well characterised lesions like ganglia and lipomas. Sometimes however, ultrasound is unable to provide a specific diagnosis. This should not be the end of things. Based on their ultrasound features, unknown lesions should be sorted into either ‘probably benign’ or ‘indeterminate/ possibly malignant’, and further follow up recommended, such as MRI or specialist assessment. Rotator cuff repair is an increasingly common procedure. It may be performed with an open or arthroscopic technique, which consists of reattachment of the torn tendon to the humeral head with suture anchors. Patients may present with residual or recurrent pain or dysfunction for which imaging is required. A repaired cuff tendon will probably never look completely normal on ultrasound. Heterogeneity, thinning, and small residual defects are common post repair, as are bursal fluid and bone surface irregularity. In general terms, if fibres can be followed to the suture anchors, then the repair is probably intact. Correlation of surgical technique and direct consultation with the surgeon may be required in difficult cases.